Microtome knife-holder

ABSTRACT

A universal knife-holder is provided comprising arms scissorpivoted at their midpoints with pairs of jaws at opposite ends to clamp knife against knife-back location stops, symmetrical opening and closing of jaw pairs being produced by pivoting of arms by means of adjusters acting between the arms and the arms being arranged for mounting in a knife sharpening machine.

United States Patent Seward et al.

[ 1 Oct. 21, 1975 MICROTOME KNIFE-HOLDER Inventors: Gerald Hugh Seward; Donald Wilson, both of Camberley, England Assignee: Shandon Southern Instruments Limited, Camberley, England Filed: Mar. 28, 1974 Appl. No.: 455,653

Foreign Application Priority Data Apr. 4, 1973 United Kingdom 16200/73 US. Cl 269/100; 51/218 R; 76/82;

269/153; 269/239 Int. Cl. B24D 15/08; 1325B 1/10 Field of Search 76/78, 82, 82.1, 82.2,

[56] References Cited UNITED STATES PATENTS 1,288,817 12/1918 Bolliger 269/238 X 1,515,286 11/1924 Svebilius 269/239 X 1,906,635 5/1933 Schick 51/218 R 3,800,632 4/1974 Juranitch 76/82 Primary Examiner-Roy Lake Assistant Examiner-Neil Abrams [57] ABSTRACT 8 Claims, 4 Drawing Figures y l g I L L r l /1" 2/ LL \17 MICROTOME KNIFE-HOLDER FIELD OF INVENTION The invention concerns the machine sharpening of microtome knives.

BACKGROUND TO THE INVENTION Traditionally, microtome knives have been sharpened by hand, an operation that is both timeconsuming and requires considerable skill on the'part of the technician. If carried out carelessly, not only is an imperfect edge obtained but the knife edge may be so damaged that its condition may only be restored by regrinding, a process which inevitably shortens the working life of the knife. In order, therefore, to avoid these substantial disadvantages of the hand sharpening technique, various forms of sharpening machine have been proposed. One such proposal which has been put into practice and has achieved considerable practical success is based upon the principle of a sharpening plate rotating eccentrically beneath a straddlemounted arbor having a knife-holder which supports a knife to be sharpened with its edge generally parallel with the arbor axis, the arbor being pivoted between alternating end positions to present opposite faces of the knife blade alternately to the surface of the sharpening plate. The knife-holder mounting on the arbor provides for some movement of the knife about an axis at right angles both to the arbor axis and the knife edge, thereby to permit self-alignment of the knife edge with the plane of the sharpening plate. A sharpening machine of this form is described, for instance, in British Pat. No. 876328.

This machine and others which have been proposed require some means of attaching a knife to be sharpened to the knife-supporting structure of the machine: in this context it is necessary to remember that microtome knives made by different manufacturers to fit their various microtomes differ widely in size and configuration so that the provision of a single attachment means which will be capable of securing knives of different sizes and different configurations to the knifesupporting structure of the machine in a satisfactory manner gives rise to obvious problems.

Ideally, a knife-holder should be adapted for attachment to a knife in such a manner that it secures the knife to the holder in a precisely determined relationship thereto, so that the holder when fitted to the sharpening machine in a standardised manner relates the knife to the machine structure in a standardised manner. This ideal may, for instance, be achieved if all the knives to be sharpened on a particular machine are of common size and configuration or, if not, have specially provided attachments e.g., tapped holes at standardised locations thereon so as to enable each of the knives to be fixed in standardised relationship to a knife-holder of common type. However, this ideal is not often attainable in practice when a single sharpening machine has to be capable of servicing the knives for all the different types of microtome that may be found in a laboratory or a laboratory complex.

THE PRIOR ART Where it is not possible or practicable to arrange for knives of different sizes and/or configuration to be provided with standardised attachments to suit a common knife-holder for a given sharpening machine, it has been the practice to use a knife-holder in the form of a fixed-jaw clamp, a knife being slidden endwise between the jaws and then driven forwardly, until securely wedged by screws or the like acting on the knife back. However, a given fixed-jaw clamp of this form is only capable of satisfactory attachment to a very limited range of knives of different sizes and/or configuration and in many cases it is necessary to provide a given sharpening machine with a substantial range of different knife-holders of this form for fitment selectively to the different knives to be serviced by that machine. Moreover, because such a knife-holder locates a knife therein by engaging its sides which are nearly parallel, flexing of the jaws under the knife-wedging stresses may permit the knife to take up a misaligned position in the holder, to the detriment of the sharpening opera tion.

THE INVENTION An object of the present invention is to provide a clamp-type knife holder which is capable of more universal application to microtome knives of different sizes and/or configuration so as to limit the number of different such knife-holders that may be needed to enable a given knife sharpening machine to service a wide range of different knives, and which proves more reliable location of a knife in a standardised position in the holder, than the fixed-jaw holders used hitherto.

Thus, a microtome knife-holder in accordance with the invention comprises a pair of complementary arms pivoted scissor-fashion to one another at their midpoints and each having an upstanding jaw member at each of its ends cooperable with the like jaw member at the corresponding end of the other arm whereby relative movement of the arms about their pivotal connection causes symmetrical opening and closing movement of the jaw member pairs at each end of the arm pair; adjusting means for accomplishing said relative pivotal movement of said arms; stop means associated with each said jaw for engagement with the back of a microtome knife extending between the jaw member pairs, for locating the knife with its edge in selected orientation relative to said arms; and means for securing the knife-holder in standardised location in a knife sharpening machine.

The means for locating such a knife-holder in standardised location in a knife sharpening machine will, of course, depend upon the construction of the knife sharpening machine with which the knife-holder is to be used. In the case, for instance, of a machine of the form described in the British Patent, in which a sharpening plate moves eccentrically beneath a straddlemounted arbor, the arbor of such machine has a knifeholder tube at its midpoint extending at right angles to the axis of the arbor and adapted to receive the spigot of a knife-holder to hold such spigot with its axis intersecting and at right angles to the arbor axis and with limited freedom for rotation about the spigot axis to permit self-aligning movement of the knife and holder, relatively to the arbor, in the manner described. A knife-holder in accordance with the present invention adapted for use with such a machine would thus have the equivalent of a spigot adapted to enter the knifeholder tube on the arbor of the machine and to be secured thereto for limited rotation therein, this spigotequivalent suitably having its axis aligned with the axis of the pivotal inter-connection between the arms of said arm pair and thus aligned with the axis of symmetry of the arm pair and jaw member pairs.

The means for adjusting the relative positions of the arms of the arm pair thereby to open and close the jaw member pairs may conveniently comprise clamping screws acting between lugs at each end of the arm pair and on the side thereof remote from the jaws. A symmetrical arrangement is preferred so that a uniform clamping force may more readily be set up between each jaw member pair and a knife extending between the jaw member pairs.

The jaw members and arms are preferably capable of flexing to a limited extent under the clamping stresses so that the jaw members may align themselves with the adjacent sides of the knife to provide line contact therewith and to accommodate minor variations in knife thickness at the respective jaw member pair locations in the length of the knife.

Desirably each said jaw member presents a concave face to the co-operating jaw member of its pair, the concavity of the face providing a surface which serves as an abutment for the back of a knife thereby to constitute, with the corresponding surface of the other jaw of its pair, the said stop means. In preferred embodiments of the invention each jaw member has a concave face defined by intersecting plane surfaces which are parallel with the longitudinal axis of the arm carrying the jaw.

Because a knife is located in the holder by engagement of its back with the said stop means and the clamping effort of the jaws on the inclined side faces of the knife tends to force the knife back against the stop means, alignment and standardised location of the knife edge is reliably achieved merely by the act of inserting the knife and closing the jaw pairs thereon.

THE DRAWINGS The accompanying drawings illustrate by way of example an embodiment of a knife-holder in accordance with the invention.

In the drawings FIG. 1 is a side elevation of the knife-holder, with a microtome knife shown held thereby;

FIG. 2 is an end elevation of the knife-holder of FIG. 1, showing how a microtrome knife is held by the jaw members;

FIG. 3 is a side elevation of one arm of the holder; and

FIG. 4 is a corresponding side elevation of the other arm of the holder.

DESCRIPTION OF ILLUSTRATED EMBODIMENT The microtome knife-holder illustrated in the drawings comprises a pair of complementary arms 1, 2 individually illustrated in FIGS. 3 and 4 respectively, these arms being pivoted together scissor-fashion at their midpoints as a result of the arm 1 having a spindle 3 extending at right angles to its length from its midpoint, the spindle 3 extending through a hole in the arm 2 and through a tubular boss 4 which extends at right angles from the midpoint of the length of the arm 2.

Each of the arms 1, 2 has an upstanding jaw member at each of its ends. Thus the arm 1 has upstanding jaw members 5, 6 at its respective ends, the jaw members 5 and 6 being offset on opposite sides of the longitudinal plane of symmetry of the arm 1 and having concave faces toward the said plane of symmetry.

Similarly the arm 2 has upstanding jaw members 7, 8 arranged at its opposite ends and on opposite sides of the longitudinal plane of symmetry with concave faces towards the latter so that the jaw members 7, 8 are opposed to the jaw members 5, 6 respectively of the arm 1. Relative pivotal movement of the arms 1 and 2 about their pivotal connection that is about the common axis of the spindle 3 and boss 4 which extends in the plane of symmetry and transversely to the opposed and overlapping faces of the arms, which extend perpendicularly to the plane of symmetry will thus cause symmetrical opening and closing movements of the jaw member pairs at each end of the arm pair.

As best seen in FIG. 2, each jaw member has a concave face presented to the co-operating jaw member of its pair, the concavity of the face providing a surface 9 which serves as an abutment for the back of a microtome knife K disposed between the jaw members of the pair. In the illustrated embodiment, the concave face of each jaw member is defined by intersecting plane surfaces both of which extend parallel with the longitudinal axis of the arm carrying the jaw member, the surface 9 being the lower of these surfaces, the other of which is shown at 10.

The arms 1 and 2 are formed integrally with their respective jaw members and with the spindle 3 and boss 4, respectively, by machining investment castings in a stainless steel, the components being hardened and tempered so as to be capable of flexing to a limited extent as necessary for the jaw members to align themselves with the adjacent sides of a knife K and provide line contact therewith while accommodating minor variations in knife thickness at the respective jaw member pair locations in the length of the knife.

Relative pivoting movement of the arms 1 and 2 is controlled by a pair of clamping screws ll, 12. Thus each of the arms 1, 2 has a screw-threaded bore 13 in a lug 14 near one of its ends, and a complementary clearance bore 15 with counterbore providing a step 16 in corresponding position in a lug 17 at the other end of the arm. Thus the clamping screw 11 or 12 as the case may be extends through the clearance bore 15 in the lug 17 of one arm and screws into the bore 13 in the lug 14 of the other arm so that tightening of that screw rocks the arms about their pivotal connection in the sense to close the jaw member pairs at the opposite ends of the arms.

The arms 1 and 2 are retained in their assembled relationship by means of a cross-pin l8 fitted in a transverse bore in the spindle 3 for co-operation with the end face of the boss 4.

The illustrated knife-holder is intended to be used in conjunction with a sharpening machine of the construction described in British Pat. No. 876328. Such a machine has a straddle-mounted arbor extending above a sharpening plate, the arbor having a knife-holder tube at its midpoint extending at right angles to the axis of the arbor for receiving the spigot of a knife-holder to hold the latter with its axis intersecting and at right angles to the arbor axis with limited freedom for rotation about the spigot axis to permit self-aligning movement of the knife and holder relatively to the arbor. The boss 4 of the knife-holder illustrated in the drawings is thus constructed to have dimensions equivalent to the aforesaid spigot of the normal knife-holder used with the machine in question, so that the illustrated knife-holder may be fitted to the knife-holder tube in the same manner as the spigot of the normal knife-holder. The spigot of the normal knife-holder has a notch in its side to receive a retaining screw extending axially of the arbor from one end thereof, for securing the spigot in the knife-holder tube; the boss 4 of the illustrated knifeholder of the invention thus has a pair of opposed notches l9, constituted by the opposite ends of a transverse bore through the boss, to co-operate with the retaining screw of the sharpening machine arbor.

Although the illustrated knife-holder has pronounced symmetry with respect to the axis of the spindle 3 it is nevertheless desirable that any microtome knife should be fitted to the holder, for sharpening, in a standardised orientation and that the knife-holder should be fitted to the sharpening machine in a standardised relationship so that that the knife will be presented to the sharpening plate of the machine in the same relationship each time the knife is to be sharpened. To facilitate recognition of a standardised relationship between a knife and the holder, and between the holder and the machine, the underside of the arm 2 is fitted with a dependent pin so as to make one end of the arm pair clearly distinguishable from the other as a guide to the user in fitting a knife in the holder and the holder and knife together to the machine.

A single knife-holder constructed in accordance with the present invention and adapted for fitment to a sharpening machine of the construction described may, for instance, be dimensioned and proportioned to be suitable for use in the sharpening of microtome knives having a length ranging from 4 inches to 10 inches with a back width ranging from 0.2 inch to 0.6 inch and having blade angles ranging between 10 and 30. Knifeholders might also be constructed in accordance with the invention and with proportions and dimensions different from those of the knife-holder just considered so as to be suitable for use with equally large ranges of knives having different lengths and back width size ranges and/or different blade angle ranges. It should therefore be understood that a set of very few such knife-holders can equip a sharpening machine to service an extremely large range of different microtome knives.

We claim:

1. A holder for a microtome knife having a back, comprising a. a pair of complementary and cooperating arms arranged on respective sides of a plane of symmetry,

each arm having 1. two ends and a face extending substantially perpendicularly to the plane of symmetry between the ends, the faces of the arms being in opposed and overlapping relationship;

b. a pivotal connection between the opposed arm faces at the midpoints thereof, the axis of the pivotal connection extending in the plane of symmetry and transversely to the opposed and overlapping arm faces;

0. an upstanding jaw member at each of the arm ends, the jaw members at the respective ends of the arms cooperating with each other upon relative pivotal movement of the arms about the pivotal connection for symmetrically closing pairs of the jaw members at each end of the pair of arms and being moved apart upon an opposite relative pivotal movement for symmetrically opening the pairs of jaw members;

d. adjusting means for accomplishing the relative pivotal movement;

e. stop means associated with each of the jaw members for engagement with the back of the microtome knife, the knife being receivable between the pairs of jaw members and being located therebetween by the stop means with an edge of the knife in a selected orientation relative to the arms; and

f. means for securing the knife holder in a knife sharpening machine.

2. The microtome knife-holder of claim 1, in which the means for accomplishing the relative movement comprise lugs at each end of the arm pair and on the side thereof remote from the jaw members, and clamping screws acting between said lugs.

3. The microtome knife-holder of claim 1, in which each said jaw member presents a concave face to the co-operating jaw member of its pair, the concavity of the face providing an abutment surface which serves as the stop means for the back of a knife.

4. The microtome knife-holder of claim 3, in which the concave face is defined by intersecting plane surfaces which are parallel with the longitudinal axis of the arm carrying the jaw.

5. The microtome knife-holder of claim 1, in which said arms and their respective jaw members are each integrally formed.

6. The microtome knife-holder of claim 1, in which said arms and jaws members are capable of flexing under knife-clamping stresses to permit of selfalignment of the jaw members with the adjacent sides of a knife clamped between the jaw member pairs.

7. The microtome knife-holder of claim 1 wherein the pivotal connection includes a spindle extending at right angles to one of said arms and a tubular boss on the other arm through which said spindle extends.

8. The microtome knife-holder of claim 7, in which said boss is dimensioned to constitute a spigot for reception in a knife-holder tube on the knife-sharpening machine to secure the knife-holder in the machine. 

1. A holder for a microtome knife having a back, comprising a. a pair of complementary and cooperating arms arranged on respective sides of a plane of symmetry, each arm having
 1. two ends and a face extending substantially perpendicularly to the plane of symmetry between the ends, the faces of the arms being in opposed and overlapping relationship; b. a pivotal connection between the opposed arm faces at the midpoints thereof, the axis of the pivotal connection extending in the plane of symmetry and transversely to the opposed and overlapping arm faces; c. an upstanding jaw member at each of the arm ends, the jaw members at the respective ends of the arms cooperating with each other upon relative pivotal movement of the arms about the pivotal connection for symmetrically closing pairs of the jaw members at each end of the pair of arms and being moved apart upon an opposite relative pivotal movement for symmetrically opening the pairs of jaw members; d. adjusting means for accomplishing the relative pivotal movement; e. stop means associated with each of the jaw members for engagement with the back of the microtome knife, the knife being receivable between the pairs of jaw members and being located therebetween by the stop means with an edge of the knife in a selected orientation relative to the arms; and f. means for securing the knife holder in a knife sharpening machine.
 2. The microtome knife-holder of claim 1, in which the means for accomplishing the relative movement comprise lugs at each end of the arm pair and on the side thereof remote from the jaw members, and clamping screws acting between said lugs.
 3. The microtome knife-holder of claim 1, in which each said jaw member presents a concave face to the co-operating jaw member of its pair, the concavity of the face providing an abutment surface which serves as the stop means for the back of a knife.
 4. The microtome knife-holder of claim 3, in which the concave face is defined by intersecting plane surfaces which are parallel with the longitudinal axis of the arm carrying the jaw.
 5. The microtome knife-holder of claim 1, in which said arms and their respective jaw members are each integrally formed.
 6. The microtome knife-holder of claim 1, in which said arms and jaws members are capable of flexing under knife-clamping stresses to permit of self-alignment of the jaw members with the adjacent sides of a knife clamped between the jaw member pairs.
 7. The microtome knife-holder of claim 1 wherein the pivotal connection includes a spindle extending at right angles to one of said arms and a tubular boss on the other arm through which said spindle extends.
 8. The microtome knife-holder of claim 7, in which said boss is dimensioned to constitute a spigot for reception in a knife-holder tube on the knife-sharpening machine to secure the knife-holder in the machine. 